Greg Troxel <[email protected]> writes: [snip]
>> I have been struggling with ZFS on a 8 to 16GB DOMU build system for >> quite a while and with this patch and setting the values to what you >> have listed I was able to perform my abuse builds without any problems >> at all. 100% workable with 4 parallel builds all using the 2 CPUs I >> give to the DOMU. Before this I could do one or two full system >> builds before I would have to reboot the build box and I was pretty >> much unable to do more than 2 parallel builds at a time without >> locking the system up. Clamping the size of the ARC seems to be the >> key. One work around I was trying to use was setting the maxvnodes to >> a very low value and that work around could be removed as well. > >> I am running this on a -current as of 2026-07-15. This find is very >> much appreciated. Thanks again. > > Interesting that you are still having lockups on current. It has a lot > of locking fixes (also in 11, not in 10). The previous kernel wasn't all that new, in fact, it was pretty old. I noted the locking fixes as they rolled by in source-change, but until now didn't have time to try anything newer. It is *entirely* possible that there is more than one thing doing on here. It is also true that I don't know if I could make a unmodified -current hang up. I was mostly just pleased to see the nice improvement. > My guess is that reducing arc is a workaround, not a fix, and is > avoiding the locking bugs by leaving more free. Still, not crashing is > good.... I don't mean to say we shouldn't merge the patch, or that it > isn't helpful to be able to set/observe -- only that there is deeper > trouble. In as much as I was able to tell, the hangs I saw mostly had to do with running out of some sort of memory in a way that the system could not recover from or could not prevent. This was the first time in a very long time that I was able to push the build system as hard as I wanted to. -- Brad Spencer - [email protected]
